Course-finder.



W. M. SISTARE.

COURSE FINDER.

APPLICATION FILED SEPIJI. I9I5.

Patented May 8, 1917.

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@Nlllllll STATE@ WILLIAM M. :SI-STARE, OF NEW LONBON, CONNECTICUT.

CQUBSE-FINDEF..

Application filed September 27, 1916.

rlhis invention relates to the art of navigation. and more particular-lv to an improved., cl'licient and practical course indei' or protractor, wherobj,1 the true 'course of a vessel between two given points maj,7 be detcrmined.

i'etofore, in navigation, the parallel ruler has been extensivelyv employed, to determine the course of the vessel, and to at tain the desired result or end in view, quite a number of moves of the rule are required.

rilheriire, one ot the objects of the present invention to overcome these disadvantages, hv providing an improved instrument olf the above kind, wl'iich is simple, c'licicnt and much easier to opera-te than the parallel ruler, b v reason of its saving time and labor, .it requiring but a single increment to lind ci' determine an;Y particu.- lar course.

l further object of the invention is to means to iind the distance in naupro'a'ide tical in s between two points, thus disicnsinn with the use of dividers. l

,in practical i'ields. the details of construe on ma)7 necessitate alterations falling within the scope what is claimed.

The inventi n comprises further features and combination of parts, as hereinafter set tor-th, shown in the drawings, and claimed.

l the drawings;-

Il Figur-c l is a plan view ot a chart, showing the instrument m use therewith, villustratino` the initial use of the same.

T1- bn n 1 nig. z/ is a ilan view or the chart. snowuse or movement of the inlng a seco--d strument.

Fig. 3 is a sectional view through the in* strument or protractor.

Fig. i is a sectional view on line 4 4 of -Fig. 3.

Fig. 5 is a detail perspective view of a thumb screw, wherebT the dial of the instrument or protractor may be held set according to the variations between the true Si eeicaten of Letters Betr-nit. parigini/(Tl Mm@ 59 3,91%

Serial No. 122,399.

north and the magnetic north et' the diagram et the compass drawn upon the chart.

Fig. 6 is a detail perspective view of the i to be swiveled upon the thumb screw, and 'to which a silk cord may be connected, wherebj,Y the cord may be extended from one given point on the chart to another given point on said chart.

Referring more especially to the drawings, l designates a conventional form or diagram of a chart tor use in navigation, showing the coast line, two predetermined points or buoys, and the usual border line ot the chart, and also the diagram of a compass, disclosing the variations between the true north 2 and the magnetic north 3 of said compass L The coast lines are designated by the numerals and 6, and the two predetermined points or buoys are denoted b v the nui 1era-ls 7 and S. lt is to be re meinbered that a chart to be used in navia considerable great distance conoit diierent sections, of which one section is shown in Fig. l, and on each section the variation between the true north and the magnetic north varies. rllhe instrument or protractor for iildfng or determining the course between the two points or buoys 7 and 8 comprises a blade il, which is tf-shaped in cross section substantially, and is dovetailcd slidabliT and transversely in a dovetail recess l0 in T-square head l1. Part 9 constitutes the T-soL .are blade. @ne end oi' the blade 9 provided wi h a reduced threaded etension l2, which is threaded into the lar t T he disk 13 l g, and mounted in the depression 15 is a circular disk i?. The disk 17 on one face is pr vided with markings indicating north, south, east and west, as shown at'lS, i9., 9,0 and 2l, and also markings or indications Qn, 23, 2li and 25, .indicating the northeast, southwest, the southeast and the northwest, and also graduations 26 subdividing these markings or indications. The disk 17 has a central opening 27, and 2S denotes a tubular thumb screw, the reduced part 29 ot which extends through the opening 2T, and is threaded into the opening 16 of the disk 13, and by tightening the thumb screw 28, the disk 17 may be held, so that the north indication may correspond or aline with the magnetic has a cen opening north of the compass l on the chart, whereby the dial of the instrument or Aprotractor may be set according to the variations between the true north and the magnetic north. It is to be notedL that the base 30 (which is adjacent the dial or disk 17 and tightens against the said dial or disk to hold it adjusted) of the thumb screw is tapering, and surrounding this base is a ring 31 having an eye 32, and by the tapering contour of said base, upward movement of the ring is prevented. However, the ring is allowed to swivel, and connected to the eye 32 is a suitable silk cord 33. Upon all sections of a chart, the scales of nautical miles or knots are used, but which in the present instance are not illustrated. However, this silk cord may be knotted, as shown in 34, or provided with any other suitable indications, corresponding to the nautical miles of the scale, and by these markings or indicationsor knots 311 of the cord, various distances upon the chart may be measured. For inland or river and lake navigation and coast navigation, this method of measuring distances may be found sufficient for practical purposes. In using the instrument or protractor, the instrument is placed on the chart so that the center of the compass 4 (which is drawn on the chart) is visible through the center of the bore of the tubular thumb screw. The T-square of the instrument is squared up accordingly. The dial or disk 17 is then set so that the north marking or indication 18 alines with the magnetic north 3, the thumb screw is then tightened to hold the dial in position. The instrument is moved, and by aid of the 'i'- square, the same is squared to the border line 35, so that the point or buoy 7 is visible through the bore 36 of the thumb screw. Having adjusted the north indication or marking 18 to correspond or aline with the magnetic north, when the instrument is placed over the compass l, the variation between the true north and the magnetic north is determined. Such variation having been determined, and the instrument placed over the buoy 7 the silk cord is then stretched or extended to aline or pass through the center of the buoy 8, and by reading oil' the dial or disk 17, the exact point where the cord passes over or through the graduations of the dial, will disclose the true course of the vessel, which, as shown in Fig. 2, is east by Gopies of this patent may be obtained for ive cents each, lcv

north, the course or direction the vessel is to be steered or guided. The instrument after having once been set according to the variations of the compass of a particular section of a chart, need not be readjusted, in order to iind the course between any other two points on the same section of chart. Of course, however, should another section of chart with different variations be used, the instrument or protractor must be readjusted according to the variations thereon.

The invention having been set forth, what is claimed as new and useful, is

1. In a device for finding courses, the combination of a blade and a circular disk on one end having an annular depression on one face, of a head transversely arranged and slidably adjustable on the blade, a direction dial pivoted in said depression, and means for holding the dial in adjusted position according to the variations of a chart compass.

2. In a device for iinding courses, the combination of a blade and a circular disk on one end having an annular depression on one face, of a head transversely arranged and slidably adjustable on the blade, a direction dial pivoted in said depression, and means for holding the dial in adjusted position ac cording to the variations of a chart compass, and a device having swiveled connections on. said means to extend between two predetermined points on a chart and extend radially from the center of the dial to determine the course relative to the variation as set on the dial.

3. In a course finder, a direction dial, a holder therefor, and a thumb screw whereby the dial may be held set according to the variations between the true and magnetic norths of a compass of a chart, said thumb screw having a tapering base, a ring swiveled on the tapering base, the taper of which prevents upward displacement of the ring, and means attached to the ring and designed te extend between two predetermined points on a chart and extending radially across the dial to find the course of a vessel relative to said variations.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM M. SISTARE.

Witnesses:

W. E PATTERSON, GEORGE D. PAcxnR.

addressing the Commissioner of Patents.

Washington, D. C. 

